Method for maintaining freshness of aquatic animals

ABSTRACT

A method and compositions for maintaining the freshness or viability of live, hard-skinned crustaceous type aquatic animals wherein in said method said animals are embedded in a granular filler composition comprising expanded vermiculite particles. The expanded vermiculite can advantageously be prepared from a dry composition comprising unexpanded vermiculite particles and a hydrogen peroxide addition compound by the addition of water thereto but expanded vermiculite made in other ways is also useful for the purpose.

United States Patent Wada et al. 1 Oct. 17, 1972 [54] METHOD FORMAINTAINING 2,328,993 9/1943 Norling ..1l9/2 FRESHNESS OF AQUATICANIMALS 2,563,364 8/1951 Proctor ..l19/2 1,016,627 2/1912 Higgins ..119/2 [72] Inventors. Takeo Wada, Kazuo Okada, Masaru Ohyama, a" ofOsaka, Japan 2,848,976 8/ 1958 Combs ..1 19/1 3,425,397 2/1969 Schulem..119/1 [73] Asslgnee: Takeda Chemical Industries, Ltd.,

Osaka Japan Primary Examiner-Aldrich F. Medbery [22] Fil d; Feb, 3, 1971Attorney-Wenderoth, Lind & Ponack [21] App]. No.: 112,409 [57] ABSTRACTA method and compositions for maintaining the fresh- [30] ForeignApphcamm M Data ness or viability of live, hard-skinned crustaceous typefi 1970 pa 12703 aquatic animals wherein in said method said animalsMarch 3, Japan are embedded in a granular filler composition comprisingexpanded vermiculite particles. The expanded U-S. vermi ulite canadvantageously- [be prepared from a [51] Int. Cl. ..A0lk 61/00 drycomposition comprising unexpanded vermiculite '[58] FleId of Search19/1-5; 99/195 particles and a hydrogen peroxide addition compound bythe addition of water thereto but expanded ver- [56] References cuedmiculite made in other ways is'also useful for the pur- UNITED STATESPATENTS P 2,266,664 12/ 1941 Stevens ..1 19/2 10 Claims, No DrawingsMETHOD FOR MAINTAINING FRESHNESS OF AQUATIC ANIMALS This inventionrelates to a method and habitat compositions for maintaining thefreshness of live, hardskinned aquatic animals in air.

It is an important but difficult problem for food industries as well asfor dealers in aquatic animals to maintain the freshness, viability orliveliness of wet aquatic animals during their transportation or storagein air; that is, from the time of being pulled out of the environmentalwater to the time of being put into use as food or bait or beingreleased again into water for further cultivation. Especially forcertain expensive varieties of hard-skinned aquatic animals such asprawns, lobsters or blue crabs, their freshness or liveliness is ofvalue and has much influence upon the purchase price. Also in theprocurement of aquatic animals for pets or for breeding purposes, it isessential to keep the animals alive for a relatively long time.

For such purposes, various measures have hitherto been developed andpracticed; for example, keeping such live animals in containers filledwith water or sawdust, and the combination of such a technique with theuse of aircraft in order to reduce the time required for the transit. Itis, however, well known that those methods are not altogether free fromdrawbacks and afford only unsatisfactory results in view of their complicated shipping procedures or still high mortality or expensivefreight rates.

The present invention provides a means for maintaining a habitat for theviability or freshness, not in water but in air, of those aquaticanimals which to have hard skins in the form of a crust or shell, andwhich include crustacea, shellfish and nereides. It has been found bythe present inventors that those hard-skinned animals can survive in asuitable layer of some expanded vermiculite particles without anysubstantial injury of the animals. It was still more surprising to findthat the expanded vermiculite particles as the filler for a package canafford a far higher survival rate of the packed animals than theconventional sawdust or the like does.

Vermiculite is a generic designation of hydrated laminar aluminosilicateminerals which have the pro perty of expanding when rapidly heated attemperatures beyond a certain critical level, and includesphillosilicates which closely resemble mica, minerals formed onhydrothermal alteration of periodotite, second-order minerals which areobtained on disintegration of micas, minerals which are recoverable fromserpentine, and hydrolyzed micas which are the products of hydrolyticalteration of biotite.

In accordance with this invention, the vermiculite is employed in anexpanded form, i.e., as expanded vermiculite. As is well known, thevermiculite tends to expand in one direction upon rapid heating, and itsvolume may be increased about 5 to times, or even about times in somematerials. In the practice of this invention, it is advantageous toemploy one which has been expanded at least 5 times, desirably 10 timesor more.

Expansion of vermiculite can be effected, for example, by rapidlyheating the vermiculite at a temperature of about 800C or higher (Theexpanded product thus obtained will hereinafter be called vermiculiteE), or by the steps of spraying the raw vermiculite evenly with anaqueous solution of hydrogen peroxide, and then heating the same at atemperature of about to C for approximately 20 minutes or so. (Theexpanded product thus obtained will hereinafter be called vermiculiteEP). Expanded vermiculites produced by any other procedures may beemployed for the present invention so far as they do not contain anyhazardous additives to the live, aquatic animals to be treated.

It is advisable to employ vermiculite in an average size of from about 1to 8 millimeters, more desirably about 1 to 5 millimeters, in at leasttwo dimensional directions.

The thus-expanded vermiculites are usually free from putrescent organicmatters which were originally present in the raw material, and, as such,afford excellent results, thanks to their improved porosity and otherbeneficial properties. In the practice of this invention, the use ofvermiculite El?(i.e. vermiculite expanded in the presence of hydrogenperoxide) is conducive to a still lower mortality of the animals.However, even with the other expanded vermiculites far better resultsare obtained than by the use of sawdust.

The live or wet, hard-skinned aquatic animals, to which this inventionis applicable, include such crustacea as prawns, lobsters, shrimps,crabs, squills or the like; such shellfishes as clams, corbicula, pondsnail, ivory shell, ark shell, trough-shell or the like; and suchannelids as nereides which are used as live bait by fishermen.

The animals are embedded, while alive, in a layer of a granular fillercomprising the expanded vermiculite particles as soon as they are pulledout of the environmental water, whether sea-water, fresh water ortherebetween as the case may be. The filler may be wet with water or theenvironmental water, but too much water is not only unnecessary butdisadvantageous in requiring particular casing, and even dry expandedvermiculite will afford a highly improved result for maintaining thefreshness of the animals. It is recommended, if circumstances permit, toembed the respective animals separately from one another in the layer offiller; in other words, to put one animal so as not to be brought intodirect contact with the other animal.

In such an embedded state, the animals can survive far longer than in aconventional filler layer, thus freshness of the animal can be retainedlonger. Furthermore, it is noteworthy that the method of the presentinvention affords an improved result even when the aquatic animals inthe embedded state are frozen as they are, compared with the case whereno filler or other conventional filler is employed. One reason thereformay reasonably be understood as due to the effect in retaining freshnessor liveliness of the animals until they are frozen. But the freezingwill naturally kill the animals at least in some cases. Nevertheless,even on such occasions a highly improved result is obtained with the useof the tiller comprising expanded vermiculite particles according to themethod of the present invention. This unexpected beneficial result ispossibly due to some extent to the heat-insulating property of theexpanded vermiculite.

As to this property, there are other interesting observations. For coldpreservation purposes in the summer and for anti-freezing purposes inthe winter,

- packing materials.

With reference to transportation of the hard-skinned aquatic animals itis conventional to use corrugated paper board boxes filled with dryrefined sawdust. Now if this sawdust bed is replaced with the samevolume of the dry expanded vermiculite filler of this invention and thesame population of the animals are embedded in this filler, the boxes,after being covered, are ready to be shipped by vehicles such as trucks,ships or aircraft in the routine manner.

The aforesaid different types of expanded vermiculites may be used asvarious mixtures, depending on the specific purpose, species of animals,any other accompanying treatment and other factors. Of course, it isalso possible to obtain the desired result by the use of the expandedvermiculites in admixture with sawdust and/or other known fillers. Theadvantageous effect of the expanded vermiculite will be eminentlyobserved whenthe granular filler comprises at least 8 percent, morepreferably 20 percent or higher, by weight of the expanded vermiculite.

Also depending upon said various factors, it is convenient to prepare,prior to the practice of the present invention, a vermiculitecomposition comprising unexpanded vermiculite particles and a hydrogenperoxide addition compound. It has also found by the present inventorsthat the composition has such a low bulk that it can be easilytransported and that such a composition can be caused to expand in situby a mere addition of water at a moderate temperature, e.g. from ambienttemperature to 100C. As for the hydrogen peroxide addition compound forthis purpose, the advantageous ones are, for example, urea-hydrogenperoxide adduct, alkali metal pyrophosphate-hydrogen peroxide adducts,alkali metal tripolyphosphate-hydrogen peroxide adducts, alkali metalorthophosphate-hydrogen peroxide adducts, alkali metalcarbonate-hydrogen peroxide adducts, alkali metal borate-hydrogenperoxide adducts, alkali metal sulfate-hydrogen peroxide adducts or thelike, said alkali metal or metals being sodium and/or potassium. Thesesalts may of course be used in form of acid salts or as a mixture ofmore than one of them, in order to yield a desired pH in the resultingexpanded vermiculite. Said premix composition can easily be prepared byadmixing any of said hydrogen peroxide adducts with the unexpandedvermiculite in a proper mixing proportion according to per seconventional blending means. The proper mixing proportion variesdepending upon the type of the adduct, intended use of the resultingexpanded vermiculite or other factors, but it is usually advantageous toemploy the hydrogen peroxide adduct in an amount of, as H from, about 50grams to about 1 kilogram, but for better results about 100 grams toabout 500 grams, per kilogram of the unexpanded vermiculite. Thusprepared premix is very handy for transportation or storage because ofits high stability and compact nature, and it can readily expand withthe addition of water or hot water at the place where the expandedvermiculite is needed. By way of example, some preferable premixcompositions are shown as follows:

l. 10 grams of unexpanded vermiculite in an average size of 2millimeters square and 4 grams of Na HPO -H 0 are evenly admixed. Thisadmixture remains unchanged upon being allowed to stand at; 25C for 1month. Upon the addition of 60cc. of hot water of 90C to the compositionit begins to expand and after about 20 minutes while kept warm, its bulkreaches about 220 cc.

2. 10 grams of unexpanded vermiculite of an average size of 1 mm. squareand 7 grams of Na P O -2H O are evenly admixed. This composition alsoremains unchanged on standing at 25C for 1 month. The addition of cc. ofhot water of C to the composition results in expansion up to cc bulk in30 minutes.

3. Urea is saturated in 10 cc. of a 35 percent aqueous I hydrogenperoxide solution at 25C, and the solution is rapidly cooled to 5C,whereupon crystals of H N CO.Nl-l -H O separate. The crystals arecollected by filtration. 5 grams of the crystals are evenly admixed.with 10 grams of unexpanded vermiculite of an average size of 2 mm.square. The admixture remains unchanged on standing at 25C for 1 month.The addition of 20 cc. of cold water and heating the resultant mixtureon a water bath for 10 minutes result in expansion up to cc. bulk.

The method of the present invention is further explained by way ofexample. In the following examples as well as the foregoing description,the abbreviations g., kg, mm., cm. and cc. mean gram(s), kilogram(s),millimeter(s), centimeter(s) and cubic centimeter(s), respectively.

EXAMPLE 1 A sheet of paper was spread on the bottom of each ofcorrugated paper boxes of the size of 42 X 30 cm. and 20 cm. in height.25 lively prawns, each weighing about 12 g., were embedded in each ofthe boxes, using as filler a sample of dry, routinely refined sawdust(for control) or the sample of either vermiculite E or vermiculite EP,so that the prawns may be spread in the layer of filler in each box. Theboxes were then covered and sealed with a tape, and kept undisturbed at12C for 72 hours. The prawns were examined and their survival rate wascalculated for each sample of the fillers. The result shows that, whilethe survival rate of the prawns in the sawdust was 20 percent, those invermiculite E and vermiculite EP were 60 percent and 80 percent,respectively.

EXAMPLE 2 In the same manner as in Example 1, 26 lively prawns wereembedded in an evenly mixed filler bed of 50 percent by weight ofvermiculite EP and 50 percent by weight of sawdust in corrugated paperboard boxes. The boxes were kept undisturbed at 12C for 72 hours, giving69 percent of the survival rate of the prawns.

EXAMPLE 3 In a similar manner to that in Example 1, 8 lively prawns,each weighing about 12 g., were embedded in each of the filler sampleslisted in Table l, and the boxes were kept undisturbed at 18C. Theprawns were examined after 24 hours and 48 hours, respectively,

rendering the respective survival rates as shown in Table l.

In each of three wooden boxes of 5 X 5 X 5 cm., 25-

lively nereides were embedded, using as filler a) seashore sand, b)vermiculite E or c) vermiculite EP,

each sample being wet with sea water. The boxes were kept undisturbed at15C. The nereides in the boxes were examinedafter 2, 3, 4 and 6 days,respectively,

giving the survival rates as shown in Table 2.

ln a similar manner to that in Example 1, 20 heads per box oflively'prawns, each weighing about 18 to 20 g., were embedded with a)sawdust, b) vermiculite EP or c) a filler consisting of 20 percent byvolume (8 percent by weight) of vermiculite EP and sawdust. For each ofthe fillers a), b) and c), five boxes were prepared, and the boxes werekept at 10C. The time to reach 80 or 50 percent of the survival rate wasobserved. Results are shown in Table 3.

TABLE 3 Filler a) Time in hours to reach 34 79 54 80% survival rate Timein hours to reach 50% survival rate 42 102 (LTM) Having thus disclosedthe invention, what is claimed is:

1. Method for maintaining the viability of a live or wet,-hard-skinned'aquatic animal in an air, habitat which comprises pullingup the aquatic animal alive from the environmental water, and embeddingthe live animal in a layer of a granular tiller comprising expandedvermiculite particles.

2. The method according to claim 1, wherein the vermiculite particlesare of an average size of about 1 to 8 millimeters in at least twodimensional directions.

3. The method according to claim 1, wherein the filler comprises atleast 8 percent by weight of the exf T $351? az i c l fig to claim 1,wherein the vermiculite is one expanded in the presence of hydrogenperoxide.

5. The method according to claim 1, wherein the aquatic animal is acrustacean.

6. The method according to claim 1, wherein the aquatic animal is ashellfish.

7. The method according to claim 1, wherein the aquatic animal is anereid.

8. A habitat for embedding crustaceous type marine life which comprisesa container substantially filled with containing a granular filler whichcomprises expanded vermiculite particles.

9. A habitat as in claim 8 wherein the tiller material comprises sawdustand expanded vermiculite particles, the said vermiculite particles beingpresent in an amount of at least 8 percent by weight of the tillermaterial.

10. A habitat as in claim 9 wherein the vermiculite particles arepresent in an amount of at least 20 percent by weight of the fillermaterial.

2. The method according to claim 1, wherein the vermiculite particlesare of an average size of about 1 to 8 millimeters in at least twodimensional directions.
 3. The method according to claim 1, wherein thefiller comprises at least 8 percent by weight of the expandedvermiculite particles.
 4. The method according to claim 1, wherein thevermiculite is one expanded in the presence of hydrogen peroxide.
 5. Themethod according to claim 1, wherein the aquatic animal is a crustacean.6. The method according to claim 1, wherein the aquatic animal is ashellfish.
 7. The method according to claim 1, wherein the aquaticanimal is a nereid.
 8. A habitat for embedding crustaceous type marinelife which comprises a container substantially filled with containing agranular filler which comprises expanded vermiculite particles.
 9. Ahabitat as in claim 8 wherein the filler material comprises sawdust andexpanded vermiculite particles, the said vermiculite particles beingpresent in an amount of at least 8 percent by weight of the fillermaterial.
 10. A habitat as in claim 9 wherein the vermiculite particlesare present in an amount of at least 20 percent by weight of the fillermaterial.